jrgordonsenior

FWIW I think you're choked up. The stock mufflers are extremely heavy and congested. An after market system, perhaps Fabspeed's, would expand your new motor's ability to breathe. Stay with the stock air box but switch to a better element, I use BMC.

4th gear is where most stock geared Porsches dyno. Mine have always been in 4th....

Here's my latest dyno sheet on a Dyno Dynamics machine. They produce considerably lower results than a Dynojet, many say 10% less. I'll have to get on a Dynojet if I want to race with NASA this year. I'll probably go to a 2.5 TB and hopefully get the WHP down to 270 or so.

Our motors are significantly different, you use the larger Nikies cylinders to get to 3.6, I used the 3.6 crank and rods with decked 3.4 heads, cams, and a 5 angle valve grind. I also have 3.8 manifolds to straight pipes, FVD's slightly enlarged throttle body, and GIAC's street flash. YMMV....




Uploaded with ImageShack.us

logray

Thanks for the offer! I remember looking at FVD's 76.4mm body years ago when I did my Softronic flash. Unfortunately, right around the time I bought the flash, Scott stopped supporting Motronic 5.2.2. Took my money and ran with it!

My T/B is stock cable op at 74.8 mm. Are you sure yours isn't 76.4mm? I don't remember a 74mm for the 996 (1998-2001), except maybe on a smaller Boxster engine. I'll send you a PM.

I would be open to throwing it on and taking it to the dyno again, which I'm starting to get the itch a little to see what was up with those torque figures.

I'm just not sure how much it could help without complimentary intake and exhaust porting. Heh maybe I could get out the dremel like speed rII did.

Interesting, even hte dyno operator Kevin noted it should be done at gear closest to 1:1 ratio. After looking at WSM, 4th gear is 1.22 and 5th is 1.02. The machine I used goes to 180mph which is about 150mph. It might take some convincing though, to get this machine spinning that fast.

It was an intertia dyno. A dynojet 424 linx, link below. As for higher numbers, I would want to see whatever is comparative, but it would also be interesting to see what it could do in 5th gear.

http://www.dynojet.com/automotive_dy...o/default.aspx

I concurr... I'm guessing a lot of the problem with mine is on the intake side, with the stock box and stock filter, 3.4L T/B, and 3.4L porting. In fact the long term fuel trims have gone a little negative with the 3.6L injectors, which might indicate the same thing, less air means less fuel right! And that AFR graph might also indicate boring-ness happening inside. You're talking to someone that used to have EvoX CAI, IPD plenum, fabspeed headers, cats, and mufflers. I also have a K&N for the stock box I removed long ago while troubleshooting my MAF. But I think I'll throw it back in just for fun. I could have the fisterD mod done on my 3.6L stock muffers, at least shipping would be cheap since he's close to me. I think I would stop at fisterD though.

I'm contemplating reflashing my DME with the softronic flash, but without any support or much info from Scott on what he "tuned" I'm a little hesitant, don't want to do any damage. The first time I bricked my DME I had to learn how to flash it on the bench, now I've flashed 3 times on 2 different DMEs without issue (both PST2 and Softronic). The 5.2.2 is difficult to flash and some of the original models had bad NVRAM.

No doubt your other mods are exploiting your upgrades, the straight pipes and the throttle body. My valves also had a grind FWIW...

logray

I nearly forgot about plugs too... geez the snowball certainly gets bigger once it starts rolling down hill.

ltusler

You're right I just measured it and it's 76mm. I think FVD opens them to 78mm? Not much thickness in the wall.

logray

PM sent on the larger T/B. Yes FVD goes to 76.4mm.

I tried looking for the 3.6L throttle body specs but couldn't find them.

For sure I think this might help, if the stock 3.4L head ports can handle the extra volume. Considering I've got the 3.6L mufflers and aftermarket headers, I am thinking this would help including the K&N w/ the stock air box.

I don't want to go crazy with mods nor tear into the engine again at this point, but I wouldn't mind giving this a go and maybe putting her back on the dyno to see if it can breathe easier.

Anyone out there know off the top what the 3.6L T/B measures out at (or would like to measure)?

jrgordonsenior

Forgot to give you A/f ratios.....

Apex996

Chew on this... The GT3 RSR has to breathe through a pair of 29mm restrictors. It makes 460 hp. Max. torque: 430 Nm at 7,250 rpm.

HazardQ

Did you ever get this resolved? I've done the exact same thing that you did, with the exact same build, (threw a rod twice on the track, so two rebuilds) and I couldn't be happier!! What a machine it is now! (I actually did a bit more, single mass flywheel, Accusump, Oil crap, Tranny work, etc.) --- BTW, Love your head bolt idea, will do that next time I tear it apart.

What is driving me bonkers though is the idle. Since the car mostly plays on the track, it's not too bad of a problem, but I still have the original stock seats, and would like to drive it on the street more.

logray

LOL!

logray

YES!!!! I did fix it!!!!

It was a combo problem. My IACV was toast, the open winding was only providing half the resistance (this was the biggest contributor). But other things that were contributing: I didn't upgrade the injectors when I upgraded the displacenent (leading to a computer induced rich condition, and even though I had swapped the injectors for larger ones the computer hadn't learned yet, it needed a reset and was still dumping too much fuel), my MAF and CPS were also marginal. ALSO, make sure you don't have any vacuum leaks. I didn't, but did a very thorough check.

Now it PUUUURRRRRSSS at idle, but I don't spend much time there (I like the other end of the tachometer better).

Oh, forgot to mention those 3.6L cans I bought from a RL member, one of them has a broken baffle inside and squeaks/rattles all over the place, so this winter it will be off to Dr Fister D for repairs.

AWDGuy

logray - hope you stillpost here

where did you get the torque specs/sequence for all the different bolts? manufacturer recommendations?

Hardback

Havn't seen Logan here for a couple years. Try Renntech's forum.

Jpere

Logray - Thanks so much for undertaking this detailed writeup ! This is an Awesome and valuable thread to a guy like me: below is why....I am not sure my below warrants a new thread (I am not sure how forums work to well...I am kind of new)...but I am looking for 1) crank specs 2)feedback on my choices.

thanks
************************

I am rebuilding a 997.1 3.8L S motor (D-chunk crack cyl 5) into a 4.0. Likely failure was a gel slug behind the water pump (wrong coolant added?)....Oil was chocolate milk mixture. (bought it this way as a project with 100K miles on it); could be gel slug was from coolant added after Dchunk failure and low coolant showed....I will never know.

Cases are coming back next week from LN Eng with nickies and JE pistons. IMS solution also being installed in the rebuild.

This will be built for street...no plan to ever race...so following decisions were made (I am open to hearing advisement if you disagree on any decision or have opinions)
1) stock rods will be reused (new bearings)
2) Using NEW OEM bolts everywhere (connecting rods, head bolts,crankcase carrier bolts etc.....I was advised if not racing..then ARP would not be needed...only really needed for the high RPM abuse of racing)
3) replacing water pump
4) Undecided on LN eng billet timing chain guide ($330) vs stock ($40) since not racing...might do it anyway for "insurance"...since it is deep in the motor)
5) all new chains and guides
6) heads were inspected at a shop..they stated guides were good...just changing the seals and resurfaced them
7) all new oil separators
8) reusing oil/coolant heat exchanger (they seem to be a suspect part from what I read even when bought new they are no always good...so if it aint broke on that one I dont want to take a chance on replacement)
9) Bought wrist pin insertion tool..plan to grind wrist pin hook away (I read this is the flat six approach) on cyl 4-6
10) will weight and match all opposing pistons+rods+rings+bolts+pins+clips for best balancing
11) Undecided but probably will send crank and all parts to shop for professional matching(to confirm my work) and crank balancing/magnaflux (This is not where this motor had a problem..so I suspect magnaflux is not needed...but insurance again comes to mind))

...lots of other smaller decisions made...but above are the bigger ones or not fully decided ones to give folks a flavor of the project

REAL question for why I am writing...I cant for the life of me find specs for 3.8L crankshaft! Info is not in the WSM. Trying to confirm Journals are in spec for standard main bearings or not so I can make my big parts buy for the rebuild.

Below are my measurements:
Crank Main Journals: Average =62.992 +.0432 / -.0292 (Max=63.03518; Min= 62.96279)
Crank Rod Journals: Average = 52.98794 +0.018 / -0.0131 (Max=53.00599; Min=52.974875 if too many sig-figs please disregard. I measured in inches the converted in excel to metric..not sure why I didnt just do metric....I am just not used to metric.

Full Disclosure: I am mech eng...but this is my first engine rebuild..I will take a few deserved lumps on this not so smart choice to make a $20K porsche high performance motor my first build....I deserve that:-); restored various previous cars and done engine swaps...just never did an engine...but I am having loads of fun!

For everyones interest Pic of Gel slug and D-chunk crack are included here Since I havent seen many when I was looking. (I do videos talking to myself for future reference...not pictures...so sorry for quality)